DESCRIPTION: (Adapted from the applicant's Description) The proposed project is designed to evaluate destructive behavior displayed by children and adolescents with developmental disabilities in the context of two studies. Behavioral research has shown that destructive behavior is often a learned (operant) behavior that is influenced by social consequences. For example, in some cases, aggression can be reinforced if it produces access to adult attention. Behavioral research has also shown that operant behavior occurs at a rate that is proportional to the rate of reinforcement for that behavior, relative to other response alternatives. This phenomenon of matching relative response rates to relative reinforcement rates has been studied under the conceptual framework of "matching theory." To date, however, little work has been done to show the practical value of matching theory in the assessment and treatment of destructive behavior. In this application, fifteen children and adolescents will be studied. In Study 1, naturally occurring response rates and reinforcement rates for destructive and appropriate behavior will be recorded and calculated according to the basic matching equation. In Study 2, reinforcement rates previously associated with destructive behavior will be applied to appropriate behavior in a reversal design.